(a) Field of the invention.
This invention relates to improvements in rotary valves, for example for use in engines such as internal combustion or compression ignition engines, pumps, compressors, and so on.
(B) Description of the prior art.
It has been proposed by M. E. Cross and A. E. Coles to improve and modify an original design of rotary valve invented by R. C. Cross, as described in Specifications of British Patents Nos. 1473107, 1478982, 1481802 and 1481803. In these proposals a two part housing is provided for the valve comprising a cap part and base part, connected by a solid hinge pin. Such an arrangement may be employed as described in the Specifications of the foregoing British Patents to control the inlet to and exhaust from an internal combustion engine in such a manner wherein a proportion of the combustion force in the cylinder is utilised to provide a self-adjusting, substantially no-clearance, seal between the valve member and its housing. Notwithstanding the effectiveness of the foregoing arrangement it has been found that the hinge pin which interconnects the cap and base parts of the split valve housing, because of its solidity, does tend to have a limiting effect on the adjustment of these two parts under variable thermal and mechanical loads. In operation, it can happen that one axial end of the valve tends to become hotter than the other and thereby to distort to a slightly conical shape the bore in which the valve member is received. This can in turn lead to leakage of gases or even seizure.